Conventionally a display device for a vehicle is described, for example in JP-2003-48453-A, which makes a driver of the vehicle recognize that the driver himself/herself is looking aside. This display device transparently displays on the front windshield of the vehicle an image flickering at a frequency corresponding to critical harmony frequencies of a portion of the retina of the driver's eye in the vicinity of the center of the retina by superimposing the flickering image.
The driver recognizes that the image is not flickering while the driver is looking forward, because the image is seen at the center of the driver's eyesight. On the other hand, the driver recognizes that the image is flickering while the driver is looking aside, because the image is seen at a peripheral portion of the driver's eyesight. Therefore, the flickering image makes the driver recognize that the driver is looking aside. Thus, the displaying device helps the driver always look forward.
However, in this case the driver tends not to look at directions other than the direction to the front. Therefore, the driver may fail to notice an object which is at a lateral side of the vehicle and has to be watched for safety of driving.
Besides, another display device of the vehicle is described, for example in JP-2000-71877-A, which provides the driver with a display of an image of a blind area at a place that corresponds well to an actual location of the blind area, which the driver cannot see.
Although this display device makes it possible for the driver to look at the image of the actual blind area, the display device does not induce the driver to look at the actual blind area.
It is an object of the present invention to improve visual ability of a driver to surrounding situations of a vehicle and making the driver attentive to the surrounding situations.